Here in Sweden is the JT sprockets well known as a good quality sprockets. Notice the JT chains and wonder about them. Anyone use them on more poweful bike(also other streetbikes) and can tell about them? Also, looking http://www.jtsprockets.com/chain?ref=cmd1 Chain X1R and Z1R, do I understand they are done dor very powerful bikes, or...what do the "avg"(average?) means before "Tensile Strenght"? Thanks!